PENSACOLA, Fla. (AP) -- BP's top executive acknowledged Thursday the global oil giant was unprepared to fight a catastrophic deepwater oil spill as engineers were forced yet again to reconfigure plans for executing their latest gambit to control the Gulf of Mexico gusher.

BP PLC planned to use giant shears to cut a pipe a mile below the sea after a diamond-tipped saw became stuck halfway through the job, another frustrating delay in six weeks of failed efforts to stop or at least curtail the worst oil spill in U.S. history. The government's point man for the disaster, Coast Guard Adm. Thad Allen, said on the NBC "Today" show the cut would be made later Thursday.

Once the riser pipe is cut, BP hopes to cap it and start pumping some crude to a surface tanker, which would reduce but not end the spill. The next chance for stopping the flow won't come until two relief wells meant to plug the reservoir for good are finished in August, after an effort to staunch the gusher with heavy mud failed Saturday.

BP Chief Executive Tony Hayward told The Financial Times it was "an entirely fair criticism" to say the company had not been fully prepared for a deepwater oil leak. Hayward called it "low-probability, high-impact" accident.

"What is undoubtedly true is that we did not have the tools you would want in your tool-kit," Hayward said in an interview published in Thursday's edition of the London-based newspaper.

The latest attempt to control the spill, the so-called cut-and-cap method, is considered risky because slicing away a section of the 20-inch-wide riser could remove kinks in the pipe and temporarily increase the flow of oil by as much as 20 percent.

Oil drifted perilously close to the Florida Panhandle's popular sugar-white beaches, and crews on the mainland were doing everything possible to limit the catastrophe.

The Coast Guard's Allen directed BP to pay for five additional sand barrier projects in Louisiana. BP said Thursday the project will cost it about $360 million, on top of about $990 million it had spent as of its latest expense update Tuesday on response and clean up, grants to four Gulf coast states and claims from people and companies hurt by the spill.

As the edge of the slick drifted within seven miles of Pensacola's beaches, emergency workers rushed to link the last in a miles-long chain of booms designed to fend off the oil. They were slowed by thunderstorms and wind before the weather cleared in the afternoon.

Forecasters said the oil would probably wash up by Friday, threatening a delicate network of islands, bays and white-sand beaches that are a haven for wildlife and a major tourist destination dubbed the Redneck Riviera.

"We are doing what we can do, but we cannot change what has happened," said John Dosh, emergency director for Escambia County, which includes Pensacola.

The effect on wildlife has grown, too.

The U.S. Fish and Wildlife Service reported 522 dead birds - at least 38 of them oiled - along the Gulf coast states, and more than 80 oiled birds have been rescued. It's not clear exactly how many of the deaths can be attributed to the spill.

Dead birds and animals found during spills are kept as evidence in locked freezers until investigations and damage assessments are complete, according to Teri Frady, a spokeswoman for the National Oceanographic and Atmospheric Administration.

"This includes strict chain-of-custody procedures and long-term locked storage until the investigative and damage assessment phases of the spill are complete," she wrote in an e-mail.

As the oil drifted closer to Florida, beachgoers in Pensacola waded into the gentle waves, cast fishing lines and sunbathed, even as a two-man crew took water samples. One of the men said they were hired by BP to collect samples to be analyzed for tar and other pollutants.

A few feet away, Martha Feinstein, 65, of Milton, Fla., pondered the fate of the beach she has been visiting for years. "You sit on the edge of your seat and you wonder where it's going," she said. "It's the saddest thing."

Officials said the slick sighted offshore consisted in part of "tar mats" about 500 feet by 2,000 feet in size.

County officials set up the booms to block oil from reaching inland waterways but planned to leave beaches unprotected because they are too difficult to defend against the action of the waves and because they are easier to clean up.

"It's inevitable that we will see it on the beaches," said Keith Wilkins, deputy chief of neighborhood and community services for Escambia County.

Florida's beaches play a crucial role in the state's tourism industry. At least 60 percent of vacation spending in the state during 2008 was in beachfront cities. Worried that reports of oil would scare tourists away, state officials are promoting interactive Web maps and Twitter feeds to show travelers - particularly those from overseas - how large the state is and how distant their destinations may be from the spill.